The present invention relates to a rotating shearing machine for the production of wooden sheared pieces starting from a log.
The production of sheared pieces takes place essentially with two machine types, to wit shearing machines with rectilinear trajectory of the blade or the log and machines with circular log trajectory. In general, these machines are called respectively vertical or horizontal shearing machines and rotating shearing machines.
In rectilinear shearing machines the log portion being processed is locked to a worktable which when moving along a rectilinear trajectory with reciprocating motion meets the blade to produce thin sheets usually 0.5 to 1.2 mm thick.
In rotating shearing machines on the other hand, the log is made to rotate around an axis parallel to its extension so that it meets the blade periodically. To rotate the log it is mounted between two powered chucks. To make the log integral with the chucks a xe2x80x9cstay logxe2x80x9d is generally used. This is a metallic structure or beam with elongated parallelepiped form on which are installed log holding systems.
The sheets obtained with the rotating shearing machine are also thin like those of rectilinear shearing machines. The substantial difference which justifies this much more complicated and difficult to build machine is that for equal log size the length of the sheets obtained is greater because in rotating machines the log cross section is intersected by the blade according to a circumference instead of a straight line as in rectilinear machines.
These machines have been used for a few dozen years just because of their greater output even if they suffer from the never eliminated disadvantage of high scrap at the beginning of the shearing of a log because of the generally tapered shape of the logs. The machine must therefore make several shearing passes to xe2x80x9cregularizexe2x80x9d the surface of the log with respect to the blade before being able to produce sheared sheets in an acceptable manner. The initial scrap is exceedingly disadvantageous when it is remembered that the most valuable wood is that obtained from the outermost layers of the plant.
The general purpose of the present invention is to remedy the above mentioned shortcomings by making available a rotating shearing machine reducing initial scrap to the minimum. Another purpose is to make available a rotating shearing machine producing sheets having different desired designs of the wood venation on the surface.
In view of this purpose it was sought to provide in accordance with the present invention a station for shearing wood sheets from a log comprising a shearing blade and a pair of chucks supporting log gripping means with the chucks being powered to rotate around an axis parallel to the blade characterized in that the gripping means are movable to change the inclination of the gripped log with respect to said chuck rotation axis.